RB1 and ovarian cancer: In addition, treatment of CSCs isolated from primary ovarian cancer samples inhibited both sphere formation and growth, demonstrating drug-induced death by Rb1 or compound K or in combination with cisplatin or paclitaxel consistently supported the in vitro observations (Rb1, CK, Rb1 + cisplatin, Rb1 + paclitaxel, compound K + cisplatin and compound K + paclitaxel, P < 0.0001) (Figure 4B).